


Isosceles

by exbex



Category: Sherlock (TV)
Genre: Cuckolding, Everyone Has Issues, F/M, Infidelity, Secrets, Unresolved Sexual Tension, Unresolved Tension
Language: English
Status: Completed
Published: 2016-01-04
Updated: 2016-01-04
Packaged: 2018-05-11 16:23:18
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 932
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5633221
Author URL: https://archiveofourown.org/users/exbex/pseuds/exbex
Summary: <blockquote class="userstuff">
      <p>The canonical series 3 pregnancy doesn't occur in this 'verse.</p>
    </blockquote>





	Isosceles

**Author's Note:**

> The canonical series 3 pregnancy doesn't occur in this 'verse.

Fiona is par for the course for him; too smart, too beautiful. She’s a bit ruthless, and has a macabre interest in her role as a pathologist that she relishes. She strikes John as what Molly would be like if Molly were less patient. She is also, possibly, the most honest person John has ever met, and John admires her for it. If Sherlock and Mycroft had a sister, maybe she would be Fiona. Of course John is drawn to her.

“I know I’m not supposed to have sex with strange men, or men that I don’t know at all, but I resent the fact that women are expected to trade freedom for safety.”

When such brutal honesty is uttered with that Irish lilt by a woman possessing style, pitch black hair, and a slight build, John is reminded of a certain other person, and feels even more depressed by how pathetic he is.

“I’m married, and my wife is sleeping with my best friend.”

Fiona examines him as she takes a sip of her wine. “And neither of them know that you know and that you secretly kind of get off on it.”

John is beginning to question whether all of this is an elaborate ruse set up to flush him out.

“Let’s go upstairs. My room.” Fiona has apparently made up her mind.

The sex is good, though it scares John a bit. Fiona insists on being fucked roughly, though John can’t bring himself to pull her hair like she asks. She seems satisfied though, her eyes half-lidded as she watches him get dressed afterwards.

“Can we do this again?” 

John pauses in pulling on his shoes. His eyes must be wide, because she laughs.

“Oh don’t look so surprised. I think you’re cute. Usually it’s the tall ones who’re broody, but you’re just the right amount of broody, and the right height too.”

John can’t help but huff an incredulous laugh. He’s been called many things, but not broody. But then, perhaps finally he’s found someone who isn’t afraid to tell him, isn’t interested in sparing his feelings.

“You’re too smart, too beautiful, and too honest. Of course I’d like to see you again.”

**

John’s been seeing a therapist, a new one. She’s more effective than Ella, not because of skill, but because she costs more and has fewer charges. She’s the one who’s insisted on   
John working on managing his anger. She’s no-nonsense telling John that he’s not so much drawn to danger as that he has some kind of hero complex.

She’s only partly right, John decides. Because hiring Raz to tail Mary and Sherlock and take pictures of them in flagrante delicto is decidedly dangerous, and not at all heroic. 

Raz tells him as much. “You’re crazy, mate.”

“If that’s your way of extorting more money out of me…”

Raz holds up his hands in a palm out gesture. “No, I’m only saying, you’re crazy, mate.”

“I can’t argue with you, Raz.”

John does nothing with the pictures, besides copying them to three flash drives. It’s a sort of stalemate, for one. The thought of losing Mary is terrifying, chest-tightening, breath-restricting terrifying. And isn’t that a turn-up? John can’t help but wish that the terror hadn’t come in sooner.

They still reach for one another, in the night. Mary’s body doesn’t lie, and John can’t quite figure out why she’s keeping up the pretense. Does she love him? Does she really want both of them? Or is this some kind of game?

**

“Seems like these would be questions for your therapist.” Fiona is sitting up in the bed, sheet wrapped hap-hazardly around her. She looks up from her phone, eyebrow raised. 

“Please tell me you have a therapist.”

“I do. I just haven’t broached this particular topic with her.”

“Do you remember me telling you that you’re just the right amount of broody? You’re starting to go over that limit.”

John has one arm behind his head, his eyes open halfway. “I won’t be offended if you kick me out of bed.”

“Well that just makes me want to keep you around, Love.”

**

John blinks, realizing that he hasn’t heard a single one of the last several words that Sherlock has spoken. He’s been too busy thinking about the long, lean lines of Sherlock’s body intertwined with the soft curves of Mary’s. Sherlock looks up exactly one second after John has crossed his legs to stamp down his own arousal. John expects to see a knowing smirk, a narrowing of the eyes, that look that says that Sherlock has just made a prime deduction. Instead there’s only irritation and an eye-roll. “Do pay attention, John.”

**

John slides his hand softly over Mary’s breast, and lets it trail down to her hip. His cock finally goes from half-mast to fully hard when he replaces the image with Sherlock’s long fingers.

“Turn over, Love.”

Mary smirks. “Oh you want it that way.” She obliges, and John positions himself behind her. “On your knees Love.”

Mary’s laugh is gorgeous, musical, seductive. “Yes Captain Watson.” John begins massaging her breasts, then lets one hand trail downward, to feel how wet and open she is. “Yes, right there Love,” she murmurs as he uses two fingers to tease her clit. He enters her and can feel her getting closer. His mouth is right next to her ear, and he nearly whispers what he knows into it, fantasizes about the shock hitting her at the same time that she climaxes. 

But to do so could change everything.

And that just wouldn’t do.


End file.
